Endoscopic Vessel Sealer and Divider Having a Flexible Articulating Shaft

ABSTRACT

An electrosurgical instrument for treating tissue includes a housing having a flexible shaft extending therefrom having an axis A-A defined therethrough. The flexible shaft has first and second jaw members attached at a distal end thereof and each jaw member includes an electrically conductive tissue contacting surface adapted to connect to a source of electrosurgical energy such that the electrically conductive tissue contacting surfaces are capable of conducting electrosurgical energy through tissue held therebetween. A drive assembly is disposed in the housing and has a first actuator operably coupled to a drive rod for reciprocation thereof and a second actuator operably coupled to the drive rod for rotation thereof. A knife is operably coupled to a distal end of the drive rod. Actuation of the first actuator moves the jaw members relative to one another for engaging tissue and actuation of the second actuator rotates the drive rod about the axis A-A to translate the knife to cut tissue disposed between the jaw members.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to U.S. ProvisionalPatent Application Ser. No. 60/850,214 entitled “ENDOSCOPIC VESSELSEALER AND DIVIDER HAVING A FLEXIBLE ARTICULATING SHAFT” filed Oct. 6,2006 by Eric Taylor et al. the entire contents of which beingincorporated by reference herein.

BACKGROUND

The present disclosure relates to an electrosurgical forceps and moreparticularly, the present disclosure relates to an endoscopicelectrosurgical forceps for sealing and/or cutting tissue utilizing anelongated, generally flexible and articulating shaft.

TECHNICAL FIELD

Electrosurgical forceps utilize both mechanical clamping action andelectrical energy to effect hemostasis by heating the tissue and bloodvessels to coagulate, cauterize and/or seal tissue. As an alternative toopen forceps for use with open surgical procedures, many modern surgeonsuse endoscopes and endoscopic instruments for remotely accessing organsthrough smaller, puncture-like incisions. As a direct result thereof,patients tend to benefit from less scarring and reduced healing time.

Generally, endoscopic surgery involves incising through body walls forexample, viewing and/or operating on the ovaries, uterus, gall bladder,bowels, kidneys, appendix, etc. There are many common endoscopicsurgical procedures, including arthroscopy, laparoscopy (pelviscopy),gastroentroscopy and laryngobronchoscopy, just to name a few. Typically,trocars are utilized for creating the incisions through which theendoscopic surgery is performed.

Trocar tubes or cannula devices are extended into and left in place inthe abdominal wall to provide access for endoscopic surgical tools. Acamera or endoscope is inserted through a relatively large diametertrocar tube which is generally located at the naval incision, andpermits the visual inspection and magnification of the body cavity. Thesurgeon can then perform diagnostic and therapeutic procedures at thesurgical site with the aid of specialized instrumentation, such as,forceps, cutters, applicators, and the like which are designed to fitthrough additional cannulas. Thus, instead of a large incision(typically 12 inches or larger) that cuts through major muscles,patients undergoing endoscopic surgery receive more cosmeticallyappealing incisions, between 5 and 10 millimeters in size. Recovery is,therefore, much quicker and patients require less anesthesia thantraditional surgery. In addition, because the surgical field is greatlymagnified, surgeons are better able to dissect blood vessels and controlblood loss.

In continuing efforts to reduce the trauma of surgery, interest hasrecently developed in the possibilities of performing procedures todiagnose and surgically treat a medical condition without any incisionin the abdominal wall by using a natural orifice (e.g., the mouth oranus) to access the target tissue. Such procedures are sometimesreferred to as endoluminal procedures, transluminal procedures, ornatural orifice transluminal endoscopic surgery (“NOTES”). Although manysuch endoluminal procedures are still being developed, they generallyutilize a flexible endoscope instrument or flexible catheter to provideaccess to the tissue target tissue. Endoluminal procedures have beenused to treat conditions within the lumen including for example,treatment of gastroesophageal reflux disease in the esophagus andremoval of polyps from the colon. In some instances, physicians havegone beyond the luminal confines of the gastrointestinal tract toperform intra-abdominal procedures. For example, using flexibleendoscopic instrumentation, the wall of the stomach can be punctured andan endoscope advanced into the peritoneal cavity to perform variousprocedures.

Using such endoluminal techniques, diagnostic exploration, liver biopsy,cholecystectomy, splenectomy, and tubal ligation have reportedly beenperformed in animal models. After the intra-abdominal intervention iscompleted, the endoscopic instrumentation is retracted into the stomachand the puncture closed. Other natural orifices, such as the anus orvagina, may also allow access to the peritoneal cavity.

As mentioned above, many endoscopic and endoluminal surgical procedurestypically require cutting or ligating blood vessels or vascular tissue.However, this ultimately presents a design challenge to instrumentmanufacturers who must attempt to find ways to make endoscopicinstruments that fit through the smaller cannulas. Due to the inherentspatial considerations of the surgical cavity, surgeons often havedifficulty suturing vessels or performing other traditional methods ofcontrolling bleeding, e.g., clamping and/or tying-off transected bloodvessels. By utilizing an endoscopic electrosurgical forceps, a surgeoncan either cauterize, coagulate/desiccate and/or simply reduce or slowbleeding simply by controlling the intensity, frequency and duration ofthe electrosurgical energy applied through the jaw members to thetissue. Most small blood vessels, i.e., in the range below twomillimeters in diameter, can often be closed using standardelectrosurgical instruments and techniques. However, if a larger vesselis ligated, it may be necessary for the surgeon to convert theendoscopic procedure into an open-surgical procedure and thereby abandonthe benefits of endoscopic surgery. Alternatively, the surgeon can sealthe larger vessel or tissue utilizing specialized vessel sealinginstruments.

It is thought that the process of coagulating vessels is fundamentallydifferent than electrosurgical vessel sealing. For the purposes herein,“coagulation” is defined as a process of desiccating tissue wherein thetissue cells are ruptured and dried. “Vessel sealing” or “tissuesealing” is defined as the process of liquefying the collagen in thetissue so that it reforms into a fused mass. Coagulation of smallvessels is sufficient to permanently close them, while larger vesselsneed to be sealed to assure permanent closure. Moreover, coagulation oflarge tissue or vessels results in a notoriously weak proximal thrombushaving a low burst strength whereas tissue seals have a relatively highburst strength and may be effectively severed along the tissue sealingplane.

More particularly, in order to effectively seal larger vessels (ortissue) two predominant mechanical parameters are accuratelycontrolled—the pressure applied to the vessel (tissue) and the gapdistance between the electrodes—both of which are affected by thethickness of the sealed vessel. More particularly, accurate applicationof pressure is important to oppose the walls of the vessel; to reducethe tissue impedance to a low enough value that allows enoughelectrosurgical energy through the tissue; to overcome the forces ofexpansion during tissue heating; and to contribute to the end tissuethickness which is an indication of a good seal. It has been determinedthat a typical fused vessel wall is optimum between 0.001 and 0.006inches. Below this range, the seal may shred or tear and above thisrange the lumens may not be properly or effectively sealed.

With respect to smaller vessels, the pressure applied to the tissuetends to become less relevant whereas the gap distance between theelectrically conductive surfaces becomes more significant for effectivesealing. In other words, the chances of the two electrically conductivesurfaces touching during activation increases as vessels become smaller.

It has been found that the pressure range for assuring a consistent andeffective seal is between about 3 kg/cm² to about 16 kg/cm² and,desirably, within a working range of 7 kg/cm² to 13 kg/cm².Manufacturing an instrument which is capable of providing a closurepressure within this working range has been shown to be effective forsealing arteries, tissues and other vascular bundles.

Various force-actuating assemblies have been developed in the past forproviding the appropriate closure forces to effect vessel sealing. Forexample, commonly-owned U.S. patent application Ser. Nos. 10/460,926 and11/513,979 disclose two different envisioned actuating assembliesdeveloped by Valleylab, Inc. of Boulder, Colo., a division of TycoHealthcare LP, for use with Valleylab's vessel sealing and dividinginstruments commonly sold under the trademark LIGASURE®. The contents ofboth of these applications are hereby incorporated by reference herein.

During use, one noted challenge for surgeons has been the inability tomanipulate the end effector assembly of the vessel sealer to grasptissue in multiple planes, i.e., off-axis, while generating theabove-noted required forces to effect a reliable vessel seal. It wouldtherefore be desirable to develop an endoscopic or endoluminal vesselsealing instrument which includes an end effector assembly capable ofbeing manipulated along multiple axes to enable the surgeon to grasp andseal vessels lying along different planes within a surgical cavity.

Endoluminal procedures often require accessing tissue deep in tortuousanatomy of a natural lumen using a flexible catheter or endoscope.Conventional vessel sealing devices may not be appropriate for use insome endoluminal procedures because of a rigid shaft that can not easilynegotiate the tortuous anatomy of a natural lumen It would therefore bedesirable to develop an endoscopic or endoluminal vessel sealinginstrument having a flexible shaft capable of insertion in a flexibleendoscope or catheter.

SUMMARY

The present disclosure relates to an electrosurgical instrument fortreating tissue which includes a housing having a flexible shaftextending therefrom with an axis A-A defined therethrough. The shaftincludes first and second jaw members attached at a distal end thereofeach including an electrically conductive tissue contacting surfaceadapted to connect to a source of electrosurgical energy. Uponelectrical activation, the electrically conductive tissue contactingsurfaces conduct electrosurgical energy through tissue held between thejaw members. A drive assembly is encased in the housing and includes afirst actuator operably coupled to a drive rod for reciprocation thereofand a second actuator operably coupled to the drive rod for rotationthereof. A knife is included and operably coupled to a distal end of thedrive rod. Actuation of the first actuator moves the jaw members from afirst position in spaced relation to one another to a second positioncloser to one another for engaging tissue. Actuation of the secondactuator rotates the drive rod about the axis A-A to translate the knifeto cut tissue disposed between the jaw members.

In one embodiment, the forceps includes a cam assembly coupled to thedistal end of the drive rod. The cam assembly includes a camming hubhaving a grooved outer periphery defined therein which is configured tomatingly engage a corresponding detent disposed on the knife. Rotationalmovement of the drive rod correspondingly rotates the camming hub which,in turn, translates the detent and knife relative to the jaw members. Acoupling device, e.g., a keyed rod, is configured at one end tointerface with the drive rod and configured at an opposite end tomatingly engage a key-like aperture defined in the camming hub.

In another embodiment, the flexible shaft includes a plurality of jointsnestingly arranged in series to form at least a portion of the flexibleshaft. Each joint may include one or more lumens defined therethroughfor allowing reciprocation of the drive rod therein. In one embodiment,each joint includes a central lumen formed therein and a pair of opposedlumens formed on either side of the central lumen. The electrosurgicalinstrument may include a pair of articulation cables slideablyextendable through the respective opposed lumens which are moveablerelative to one another to articulate the shaft relative to axis A-A.

In yet another embodiment, a third actuator may be included which isoperably coupled to the housing for moving the pair of articulationcables relative to one another for articulating the flexible shaftrelative to axis A-A.

The present disclosure also relates to an electrosurgical instrument fortreating tissue which includes a housing having a flexible shaftextending therefrom including an axis A-A defined therethrough. An endeffector assembly is attached at the distal end of the shaft whichincludes a clevis for supporting first and second jaw members about apivot pin such that the jaw members are moveable relative to oneanother. Each jaw member includes an electrically conductive tissuecontacting surface adapted to connect to a source of electrosurgicalenergy such that the electrically conductive tissue contacting surfacesare capable of conducting electrosurgical energy through tissue heldtherebetween. The jaw members each include an angled cam surface definedtherein and the clevis includes a slot defined therein. A knife isoperably coupled to a distal end of the drive rod and a drive assemblyis disposed in the housing. The drive rod assembly includes a firstactuator operably coupled to a drive rod for reciprocation thereof and asecond actuator operably coupled to the drive rod for rotation thereof.The distal end of the drive rod is configured to receive a drive pinwhich engages both the cam surface defined in the jaw members and theslot defined in the clevis such that actuation of the first actuatorreciprocates the drive pin to move the jaw members from a first positionin spaced relation to one another to a second position closer to oneanother for engaging tissue and actuation of the second actuator rotatesthe drive rod about the axis A-A to translate the knife to cut tissuedisposed between the jaw members.

In one embodiment, a cam assembly is coupled to the distal end of thedrive rod which includes a camming hub having a grooved outer peripherydefined therein. The grooved outer periphery is configured to matinglyengage a corresponding detent disposed on the knife wherein rotationalmovement of the drive rod correspondingly rotates the camming hub which,in turn, translates the detent and knife relative to the jaw members.The drive rod is slidingly received within the camming hub such thataxial movement of the drive road does not reciprocate the knife.

The present disclosure also relates to an electrosurgical instrument fortreating tissue which includes a housing having a shaft extendingtherefrom having an axis A-A defined therethrough. The shaft is at leastpartially flexible and includes first and second jaw members attached ata distal end thereof. Each jaw member includes an electricallyconductive tissue contacting surface adapted to connect to a source ofelectrosurgical energy such that the electrically conductive tissuecontacting surfaces are capable of conducting electrosurgical energythrough tissue held therebetween. A drive assembly is disposed in thehousing and has a first actuator operably coupled to a flexible driverod for reciprocation thereof to move the jaw members from a firstposition in spaced relation to one another to a second position closerto one another for engaging tissue. A second actuator is disposed on thehousing and is actuatable to articulate the shaft.

In one embodiment, the flexible portion of the shaft includes aplurality of joints nestingly arranged in series. Each joint may beconfigured to include one or more lumens defined therethrough forallowing reciprocation of the drive rod and articulation cables therein.

In one embodiment, the second actuator includes an articulation assemblyhaving one or more user actuatable components (e.g., wheels) disposed onthe housing which are operably coupled to a pulley system forreciprocating the articulation cables through the shaft. Thearticulation assembly may also include one or more guides for directingthe pair of articulation cables into the pulley system and forpre-tensioning the articulation cables.

In another embodiment, the drive assembly includes a four bar mechanicallinkage operably coupled to a drive rod wherein actuation of the fourbar mechanical linkage reciprocates the drive rod which, in turn, movesthe jaw members from a first position in spaced relation to one anotherto a second position closer to one another for engaging tissue.

In yet another embodiment, an adjustment actuator is coupled to thedrive rod which allows a manufacturer to adjust the relative distance ofthe jaw members when disposed in the first position.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein:

FIG. 1 is a perspective view of an endoscopic forceps showing a housing,a flexible shaft and an end effector assembly according to the presentdisclosure;

FIG. 2 is an enlarged front, perspective view of the flexible shaft(without an outer casing) and the end effector assembly of FIG. 1;

FIG. 3 is an enlarged rear, perspective view of the flexible shaft andend effector assembly with parts separated;

FIG. 4 is a greatly-enlarged perspective view of a cam mechanism of theend effector assembly;

FIG. 5 is a side cross section of the flexible shaft and end effectorassembly of FIG. 2 shown in an open configuration;

FIG. 6 is a side cross section of the flexible shaft and end effectorassembly of FIG. 2 shown in a closed configuration;

FIG. 7 is a side cross section of the flexible shaft and end effector ofFIG. 2 showing distal translational movement of a cutting mechanismconfigured to cut tissue disposed within jaw members of the end effectorassembly;

FIG. 8 is a longitudinal, cross-sectional view of the end effectorassembly of FIG. 2 in an un-articulated condition;

FIG. 9 is a longitudinal, cross-sectional view of the end effectorassembly of FIG. 2 in an articulated condition.

FIG. 10 is a cross-section of the housing showing the internal,electrical routing of an electrosurgical cable and electrical leads;

FIG. 11 is a greatly-enlarged view of the indicated area of detail ofFIG. 10;

FIG. 12 is a perspective view of another embodiment of an endoscopicforceps showing a housing, a partially flexible shaft and an endeffector assembly according to the present disclosure; of FIG. 12;

FIG. 13 is an enlarged perspective view of the partially flexible shaftFIG. 14A is an enlarged, exploded perspective view of the partiallyflexible shaft of FIG. 13;

FIG. 14B is a greatly enlarged perspective view of a fine adjustmentmechanism of according to the present disclosure;

FIG. 14C is an exploded perspective view of the housing of the forcepsof FIG. 12;

FIG. 15A is a rear perspective of the housing showing various internalcomponents disposed therein;

FIG. 15B is a front perspective of the housing showing various internalcomponents disposed therein;

FIG. 16A is a side cross section of the partially flexible shaft of FIG.13 with end effector assembly shown in open configuration;

FIG. 16B is a front perspective of the partially flexible shaft of FIG.13 with end effector assembly shown in open configuration;

FIG. 16C is a bottom perspective of the partially flexible shaft of FIG.13 with end effector assembly shown in partially open configuration;

FIG. 17A is a side cross section of the partially flexible shaft of FIG.13 with end effector assembly shown in closed configuration;

FIG. 17B is a front, internal perspective of the partially flexibleshaft of FIG. 13 with end effector assembly shown in closedconfiguration;

FIG. 18A is an enlarged internal perspective of an articulation assemblyin accordance with the present disclosure;

FIG. 18B is a top cross section of the partially flexible shaft of FIG.13 in an aligned, non-articulated orientation;

FIG. 18C is a top cross section of the partially flexible shaft of FIG.13 in an articulated orientation;

FIG. 19A is a side cross section of the housing showing the forceps in asubstantially closed orientation;

FIG. 19B is a side cross section of the housing showing the forceps in asubstantially open orientation; and

FIGS. 20A-20B are enlarged side perspective views of a gear member andarticulation wheel of the articulation assembly.

DETAILED DESCRIPTION

The present disclosure relates to an electrosurgical forceps and moreparticularly, the present disclosure relates to an endoscopicelectrosurgical forceps for sealing and/or cutting tissue utilizing anelongated, generally flexible and articulating shaft. In one embodiment,for example, such a device comprises a handle, handle assembly or othersuitable actuating mechanism (e.g., robot, etc.) connected to a proximalend of a flexible, elongated body portion or shaft. A distal portion ofthe flexible shaft includes an articulating portion comprised of one ormore joints to allow articulation of an end effector away from thelongitudinal axis in response to actuation of articulation cables. Anend effector is operatively supported on a distal end of the flexibleshaft. The end effector includes a pair of jaws that can be actuatedbetween a closed position and an open position. The jaws are adapted tosupply electrical energy to tissue grasped between the jaws. The endeffector also includes a knife assembly that can be actuated to cuttissue grasped within the jaws.

The functions of opening and closing the jaws; operating the knifeassembly; and articulating the end effector can be performed remotelyfrom the handle by actuation of various mechanisms in the handle.Mechanical motion may be transmitted from the handle through theflexible shaft to the end effector by flexible cables or rods within theflexible shaft. For example, in one embodiment two cables are used toprovide articulation; one push-pull style cable opens and closes thejaws; and a second push-pull style cable actuates the knife assembly.The device is adapted to be placed in a lumen of a flexible endoscopeand then inserted into a natural orifice of a patient and transitedendoluminally through the anatomy of the natural lumen to a treatmentsite within or outside the natural lumen.

Turning now to FIGS. 1-3, one embodiment of an endoscopic vessel sealingforceps 10 is shown for use with various surgical procedures andgenerally includes a housing 20, a handle assembly 30, a rotatingassembly 80, an articulation assembly 90, a trigger assembly 70 and anend effector assembly 100 which mutually cooperate to rotate,articulate, grasp, seal and divide tubular vessels and vascular tissue.Although the majority of the figure drawings depict a bipolar sealingforceps 10 for use in connection with endoscopic surgical procedures,the present disclosure may be used for monopolar surgical procedureswhich employ a remote patient pad for completing the current loop.

Forceps 10 includes a generally flexible shaft 12 which has a distal end16 dimensioned to mechanically engage the end effector assembly 100 anda proximal end 14 which mechanically engages the housing 20. In oneembodiment, the shaft 12 has at least two portions, a proximal portionand a distal portion. The proximal portion of the shaft may be formed ofa flexible tubing (e.g., plastic) and may incorporate a tube of braidedsteel to provide axial (e.g., compressional) and rotational strength.The distal portion of shaft 12 may be also be flexible, but mayincorporate one or more moving joints. A casing 12′ may be employed toprotect a plurality of internal moving joints 12 a of the flexible shaft12.

In one embodiment, the proximal portion of the shaft is flexible andnon-articulating while the distal portion of shaft 12 is capable ofarticulating in response to movement of articulation cables or wires.Details of how the shaft 12 flexes are described in more detail belowwith respect to FIGS. 8 and 9. The proximal end 14 of shaft 12 isreceived within the housing 20 and connected to the rotating assembly80, articulating assembly 90 and drive assembly 150. In the drawings andin the descriptions which follow, the term “proximal,” as istraditional, will refer to the end of the forceps 10 which is closer tothe user, while the term “distal” will refer to the end which is fartherfrom the user.

As best seen in FIG. 1, forceps 10 also includes an electrosurgicalcable 310 which connects the forceps 10 to a source of electrosurgicalenergy, e.g., a generator (not shown). It is contemplated thatgenerators such as those sold by Valleylab—a division of Tyco HealthcareLP, located in Boulder, Colo. may be used as a source of electrosurgicalenergy, e.g., Valleylab's LIGASURE™ Vessel Sealing Generator andValleylab's Force Triad™ Generator.

The generator may include various safety and performance featuresincluding isolated output, independent activation of accessories and/orso-called “Instant Response™” software which is a proprietary technologyowned by Valleylab—a division of Tyco Healthcare LP. Instant Response™is an advanced feedback system which senses changes in tissue 200 timesper second and adjusts voltage and current to maintain appropriatepower. The Instant Response™ technology is believed to provide one ormore of the following benefits to vessel sealing: consistent clinicaleffect through all tissue types; reduced thermal spread and risk ofcollateral tissue damage; less need to “turn up the generator”; anddesigned for the minimally invasive environment.

Cable 310 is internally divided into cable lead 310 a, 310 b and 310 cwhich each transmit electrosurgical energy through their respective feedpaths through the forceps 10 to the end effector assembly 100 asexplained in more detail below with respect to FIGS. 10 and 11.

Handle assembly 30 includes a fixed handle 50 and a movable handle 40.Fixed handle 50 is integrally associated with housing 20 and handle 40is movable relative to fixed handle 50 as explained in more detail belowwith respect to the operation of the forceps 10. Rotating assembly 80may be integrally associated with the housing 20 and is rotatable viarotating wheel 82 approximately 180 degrees in either direction about alongitudinal axis “A-A” defined through shaft 12. One envisionedrotating assembly 80 is disclosed in commonly-owned U.S. patentapplication Ser. No. 10/460,926. Another envisioned rotating assembly isdisclosed in commonly-owned U.S. patent application Ser. No. 11/519,586.The entire contents of both applications are incorporated by referenceherein.

Articulation assembly 90 may also be integrally associated with housing20 and operable via wheel 92 to move the end effector assembly 100 inthe direction of arrows “B-B” relative to axis “A-A”. Wheel 92 may beprovided in alternative arrangements such as disposed on the side ofhousing. Also, wheel 92 may be replaced by other mechanisms to actuatethe articulation assembly 90 such as a levers, trackballs, joysticks, orthe like. Details relating to the articulation assembly 90 are explainedin more detail below with reference to FIGS. 8 and 9.

As mentioned above, end effector assembly 100 is attached at the distalend 16 of shaft 12 and includes a pair of opposing jaw members 110 and120. Movable handle 40 of handle assembly 30 is ultimately connected toa drive assembly 150 which, together, mechanically cooperate to impartmovement of the jaw members 110 and 120 from an open position whereinthe jaw members 110 and 120 are disposed in spaced relation relative toone another, to a clamping or closed position wherein the jaw members110 and 120 cooperate to grasp tissue therebetween.

Turning now to the more detailed features of the present forceps housing20, shaft 12 and end effector assembly 100, movable handle 40 isselectively movable about a pivot pin 29 from a first position relativeto fixed handle 50 to a second position in closer proximity to the fixedhandle 50 which, as explained below, imparts movement of the jaw members110 and 120 relative to one another. The movable handle include a clevis45 which forms a pair of upper flanges each having an aperture at anupper end thereof for receiving the pivot pin 29 therethrough. In turn,pin 29 mounts to opposing sides of the housing 20.

Clevis 45 also includes a force-actuating flange or drive flange (notshown) which aligns along longitudinal axis “A-A” and which abuts thedrive assembly 150 such that pivotal movement of the handle 40 forcesactuating flange against the drive assembly 150 which, in turn, closesthe jaw members 110 and 120. A lower end of the movable handle 40includes a flange 91 which is mounted to the movable handle 40 and whichincludes a t-shaped distal end 95 that rides within a predefined channel51 disposed within fixed handle 50 to lock the movable handle 40relative to the fixed handle 50.

The end effector assembly 100 includes opposing jaw members 110 and 120which cooperate to effectively grasp tissue for sealing purposes. Theend effector assembly 100 may be designed as a unilateral assembly,i.e., jaw member 120 is fixed relative to the shaft 12 and jaw member110 pivots about a pivot pin 103 to grasp tissue or a bilateralassembly, i.e., both jaw members 110 and 120 move relative to axis“A-A”. A drive rod 142 or drive sleeve is operably coupled to the driveassembly 150 and is selectively reciprocable via movement of handle 40relative to handle 50 to actuate, i.e., pivot, the jaw members 110 and120 relative to one another. In an embodiment of the device, drive rod142 is flexible, and may be, for example, a cable.

In one particular embodiment according to the present disclosure and asbest illustrated in FIGS. 1-3, a knife channel 115 a and 115 b may bedefined in the upper and/or lower jaw member 110 and 120, respectively.The knife channel 115 a and 115 b is dimensioned to run through thecenter of the jaw members 110 and 120, respectively, such that a blade185 may be selectively reciprocated to cut the tissue grasped betweenthe jaw members 110 and 120 when the jaw members 110 and 120 are in aclosed position. Blade 185 may be configured (or the blade 185 incombination with the end effector assembly 100 or drive assembly 150)such that the blade 185 may only be advanced through tissue when the jawmembers 110 and 120 are closed thus preventing accidental or prematureactivation of the blade 185 through the tissue.

As best shown in FIGS. 2 and 3, jaw member 110 includes an insulativejaw housing 114 and an electrically conducive surface 112. Insulator 114is dimensioned to securely engage the electrically conductive sealingsurface 112 by stamping, by overmolding, by overmolding a stampedelectrically conductive sealing plate and/or by overmolding a metalinjection molded seal plate. All of these manufacturing techniquesproduce jaw member 110 having an electrically conductive surface 112which is substantially surrounded by an insulative jaw housing 114. Jawmember 110 may also include one or more wire guides or channels (notshown) which are designed to guide cable lead 311 into electricalcontinuity with sealing surface 112.

Electrically conductive surface 112 and insulative jaw housing 114, whenassembled, form a longitudinally-oriented slot 115 a definedtherethrough for reciprocation of the knife blade 185. It is envisionedthat the knife channel 115 a cooperates with a corresponding knifechannel 115 b defined in jaw member 120 to facilitate longitudinalextension of the knife blade 185 along a preferred cutting plane toeffectively and accurately separate the tissue along the formed tissueseal.

Jaw member 120 includes similar elements to jaw member 110 such as aninsulative jaw housing 124 and an electrically conductive sealingsurface 122 which is dimensioned to securely engage the insulative jawhousing 124. Likewise, the electrically conductive surface 122 and theinsulative jaw housing 124, when assembled, include alongitudinally-oriented channel 115 a defined therethrough forreciprocation of the knife blade 185. As mentioned above, when the jawmembers 110 and 120 are closed about tissue, knife channels 115 a and115 b allow longitudinal extension of the knife 185 in a distal fashionto sever tissue along the tissue seal. A single knife channel, e.g., 115b, may be completely disposed in one of the two jaw members, e.g., jawmember 120, depending upon a particular purpose. Jaw member 120 may beassembled in a similar manner as described above with respect to jawmember 110.

Jaw member 120 includes a series of stop members 750 disposed on theinner facing surfaces of the electrically conductive sealing surface 122to facilitate gripping and manipulation of tissue and to define a gap“G” (see FIG. 7) between opposing jaw members 110 and 120 during sealingand cutting of tissue. The preferred gap “G” between the conductivesealing surfaces 112 and 122 to effectively and reliably seal tissue isbetween about 0.001 and about 0.006 inches. Stop members 750 may beemployed on one or both jaw members 110 and 120 depending upon aparticular purpose or to achieve a desired result. Stop members 750 maybe thermally sprayed atop the electrically conductive sealing plate 122or deposited or affixed in any other known fashion in the art. Moreover,the stop members 750 may be disposed in any configuration along theelectrically conductive jaw surfaces 112 and 122 depending upon aparticular jaw configuration or desired surgical result.

In one embodiment, jaw members 110 and 120 are engaged to the end ofshaft 12 (or a sleeve (not shown) surrounding shaft 12) and are operable(via rotating assembly 80) to rotate about pivot 103 of the end effectorassembly 100. Lead 311 carries a first electrical potential to jawmember 110 and a second electrical potential is transferred throughdrive rod 142 (or, alternatively, the above mentioned sleeve) to jawmember 120. Upon activation, the two electrical potentials transmitelectrical energy through tissue held between conductive seal plates 112and 122. Details relating to one envisioned electrical configuration ofthe lead 311 through forces 10 are discussed with reference to FIGS. 10and 11 below.

Proximal movement of the drive rod 142 pivots the jaw members 110 and120 to a closed position. More particularly, once actuated, handle 40moves in a generally arcuate fashion towards fixed handle 50 about pivotpin 29 which forces clevis 45 to pull reciprocating drive rod 142 in agenerally proximal direction to close the jaw members 110 and 120.Moreover, proximal rotation of the handle 40 causes the locking flange71 to release, i.e., “unlock”, the trigger assembly 70 for selectiveactuation of the knife 185.

The operating features and relative movements of the internal workingcomponents of one envisioned forceps 10, i.e., drive assembly 150,trigger assembly 70 and rotational assembly 80 are all described incommonly-owned U.S. patent application Ser. No. 10/460,926, the entirecontents of which are incorporated herein.

As mentioned above, the jaw members 110 and 120 may be opened, closed,rotated and articulated to manipulate and grasp tissue until sealing isdesired. This enables the user to position and re-position the forceps10 prior to activation and sealing. As illustrated in FIG. 4, the endeffector assembly 100 is rotatable about longitudinal axis “A-A” throughrotation of the rotating knob 82 of rotating assembly 80. The endeffector assembly 100 may also be articulated in either direction in thedirection of arrows “B-B” as explained in more detail below withreference to FIGS. 8 and 9. Once the tissue is grasped (within therequired pressure range of about 3 kg/cm² to about 16 kg/cm²), the userthen selectively applies electrosurgical energy to effectively sealtissue. Once sealed, the user then selectively advances the knife 185 byactuating the trigger assembly 70 to cut the tissue along the tissueseal.

The operating features and relative movements of one envisioned triggerassembly 70 are described in the above-mentioned commonly-owned U.S.patent application Ser. No. 10/460,926. In one embodiment, for example,actuation of the trigger assembly 70 causes a cable extending throughshaft 12 and operatively coupled to knife 185 to move distally tothereby cut tissue along the tissue seal. In another embodiment, triggerassembly includes gearing that translates actuation of the triggerassembly to rotational motion of a cable extending through shaft 12.

One envisioned drive assembly 150 is also disclosed in U.S. patentapplication Ser. No. 10/460,926 which involves the selectivereciprocation of a sleeve to open and close the jaw members 110 and 120.Another envisioned embodiment is described in U.S. application Ser. No.11/519,586 wherein the drive assembly pulls a drive rod to open andclose the jaw members 110 and 120.

With particular respect to FIGS. 2 and 3, the forceps 10 includes aplurality of joints 12 a which are nestingly arranged in series to formflexible shaft 12. The distal end 16 of shaft 12 mechanically engagesthe end effector assembly 100 and the proximal end 14 of the shaft 12mechanically engages the housing 20. Each of the plurality of joints 12a of the flexible shaft 12 includes a distal knuckle 12 b and a proximalclevis 12 c formed therewith. Each knuckle 12 b operatively engages aclevis 12 c of an adjacent joint 12 a. Each joint 12 a defines a centrallumen 12 d formed therein and a pair of opposed lumens 12 e formed oneither side of central lumen 12 d. A pair of articulation cables 94 aand 94 b slideably extend through respective lumens 12 e of joints 12.The operation of cables 94 a and 94 b is explained in further detailbelow with respect to FIGS. 8 and 9.

As seen in FIG. 3, end effector assembly 100 includes a jaw supportmember 222 which is configured to pivotably support jaw members 110 and120. Jaw support member 222 defines a lumen 224 in a proximal endthereof and a pair of spaced apart arms 226 a and 226 b in a distal endthereof. Lumen 224 is configured and dimensioned to receive a stem 12 fextending from a distal-most joint 12 a of flexible shaft 12. Lumen 224defines a pair of opposed channels 224 a, 224 b in a surface thereofwhich are configured to slidingly receive the knife blade 185 forreciprocation therein.

Jaws 110 and 120 are pivotably mounted on support member 222 by a jawpivot pin 234 which extends through apertures 228 formed in arms 226 aand 226 b of support member 222 and respective pivot slots 132 a, 132 bformed in jaw members 110 and 120. To move jaws 110 and 120 between anopen position and a closed position, an axially or longitudinallymovable center rod 136 having a camming pin 138 is mounted within jawsupport 222 at the center rod's 136 distal end 136 a thereof. Cammingpin 138 rides in and engages angled camming slots 132 a and 132 b formedin respective jaw members 110 and 120 such that axial or longitudinalmovement of the center rod 136 via drive rod 142 causes jaws 110 and 120to cam between open and closed positions.

End effector assembly 100 also includes a keyed rod 140 having a distalend 140 a rotatably connected to a proximal end 136 b of center rod 136.Keyed rod 140 includes a proximal end 140 b fixedly connected to adistal end of drive rod 142, and a body portion 140 c, disposed betweendistal end 140 a and proximal end 140 b, having a non-circularcross-sectional profile.

End effector assembly 100 further includes a camming assembly 141including a camming hub 144 having a lumen 144 a defined therethroughconfigured and adapted to slidably receive body portion 140 c of keyedrod 140 therein. Camming hub 144 includes a mating mechanical interfacedefined therein which cooperates with the outer peripheral configurationof body portion 140 c of keyed rod 140 to allow positive engagement ofthe two component halves for rotational purposes as explained in moredetail below. The camming hub 144 also includes a helical or spiralgroove 144 b defined in an outer surface thereof which is configured tomechanically engage a detent 187 of the knife 185 the purpose of whichis also explained in more detail below. Camming hub 144 is configuredfor rotatable disposition within lumen 124 of support member 222. In analternative embodiment, camming hub 144 may be replaced by othermechanisms to translate rotational motion to linear motion (e.g., a leadscrew, one or more gears, and the like).

In operation, the drive rod 142 is configured to provide two distinctand separate functions: axial displacement thereof actuates the jawmembers 110 and 120 between the open to closed positions and rotationalmovement thereof advances the knife 185 through tissue. Moreparticularly, axial displacement of drive rod 142 imparts axialdisplacement to keyed rod 140 which, in turn, imparts axial displacementto center rod 136. However, since camming hub 144 is axially slidablysupported on keyed rod 140, no axial displacement is imparted thereto.As best shown in FIGS. 5 and 6, proximal translation of the drive rod142 in the direction of arrow “F” forces camming pin 138 proximallywithin camming slots 132 a and 132 b to close the jaw members 110 and120 about tissue with the requisite closure pressure and within therequisite gap “G” range. In an alternative embodiment (not shown), thefunctions actuated by drive rod 142 may be reversed with axialdisplacement advancing the knife 185 and rotational motion opening andclosing jaw members 110 and 120. The electrically conductive sealingplates 112 and 122 are then energized to transmit electrical energythrough tissue held between the jaw members 110 and 120.

One or more safety features may be employed either mechanically withinthe forceps 10 or electrically within the generator (not shown) toassure that tissue is effectively grasped between the jaw members 110and 120 before energy is supplied.

Once a proper tissue seal is formed, the tissue may be severed along thetissue seal. Again, one or more safety features may be employed toassure that a proper seal has been formed prior to severing tissue. Forexample, the generator may include a safety lockout which electricallyprevents or electro-mechanically prevents actuation of the knife 185unless a proper and effective seal has been formed. As mentioned above,it is also important to note that vessel or tissue sealing is more thansimply coagulating tissue and requires precise control of pressure,energy and gap “G” to effectively seal tissue.

The present disclosure incorporates a knife 185 which, when activatedvia the trigger assembly 70, progressively and selectively divides thetissue along an ideal tissue plane in precise manner to effectively andreliably divide the tissue into two sealed halves. The knife 185 allowsthe user to quickly separate the tissue immediately after sealingwithout substituting a cutting instrument through a cannula or trocarport. As can be appreciated, accurate sealing and dividing of tissue isaccomplished with the same forceps 10.

It is envisioned that knife blade 185 may also be coupled to the same oran alternative electrosurgical energy source to facilitate separation ofthe tissue along the tissue seal. Moreover, it is envisioned that theangle of the knife blade tip 185 a may be dimensioned to provide more orless aggressive cutting angles depending upon a particular purpose. Forexample, the knife blade 185 may be positioned at an angle which reduces“tissue wisps” associated with cutting. More over, the knife blade 185may be designed having different blade geometries such as serrated,notched, perforated, hollow, concave, convex etc. depending upon aparticular purpose or to achieve a particular result. It is envisionedthat the knife 185 generally cuts in a progressive, uni-directionalfashion (i.e., distally). As mentioned above, the drive rod performs twofunctions, opening and closing the jaw members 110 and 120 and advancingthe knife 185 to sever tissue (see FIG. 7). In order to sever thetissue, rotation of drive rod 142 imparts rotation to keyed rod 140which, in turn, imparts rotation to camming hub 144. However, sincekeyed rod 140 is rotatably connected to center rod 136, no rotation isimparted thereto.

End effector assembly 100 is operably coupled to a knife 185 which isslidably supported within respective channels 224 a and 224 b of supportmember 222. More particularly, knife 185 includes a sharpened orserrated edge 185 a at a distal end thereof and a pair of guide flanges186 a and 186 b which extend proximally therefrom. The proximal end offlange 186 a includes a detent or protrusion 187 which is configured toengage and ride within spiral or helical groove 144 b defined in camminghub 144.

In operation, as camming hub 144 is rotated in direction of arrow “C”,proximal end 187 rides within groove 144 b of camming hub 144 and movesin an axial direction “A1” relative thereto. Rotation of the camming hub144 in one direction forces the blade 185 distally through knifechannels 115 a and 115 b in jaw members 110 and 120, respectively, tosever tissue disposed therebetween. Rotation in the opposite directionforces proximal end 187 proximally to retract blade 185 to aproximal-most position. A spring may be operatively associated with thecamming hub 144 to bias the knife 185 in a proximal-most orientation.

As mentioned above, the end effector assembly 100 may also beselectively articulated. More particularly, as seen in FIG. 8 with endeffector assembly 100 in an axially aligned condition, in order toarticulate end effector assembly 100 via articulation assembly 90, wheel92 is configured to rotate in a first direction to move end effectorassembly 100 in a corresponding first direction and rotate in anopposite direction to move end effector assembly 100 in an oppositedirection. Various pulley assemblies and gearing assemblies may beemployed to accomplish this purpose.

For example, in one embodiment, the handle assembly may include at leastone articulation cable operable from the housing. Each articulationcable includes a distal end operatively connectable with an end effectorand a proximal end operatively connected to at least one of a controlelement, such as, for example, a slider, dial, lever, or the like,supported on the housing. In operation, movement of the control elementresults in movement of the at least one articulation cable, whereinmovement of the at least one articulation cable in a first directioncauses an articulation of the end effector and movement of the at leastone articulation cable in a second direction results in articulation ofthe end effector in a second direction.

A pair of articulation cables may be provided each having a proximal endoperatively connected to the control element such that movement of thecontrol element in a first direction results in movement of a firstarticulation cable in a first direction and movement of a secondarticulation cable in a second direction; and movement of the controlelement in a second direction results in movement of the firstarticulation cable in the second direction and movement of the secondarticulation cable in the first direction.

More particularly and with reference to FIGS. 8 and 9, when firstarticulation 94 b cable (i.e., the lower articulation cable as depictedin FIGS. 8 and 9) is withdrawn in a proximal direction via wheel 92, asindicated by arrow “D” of FIG. 9, a distal end of articulation cable 94b, anchored to a distal-most joint 12 a, rotates about the interfacebetween knuckles 112 b and clevis' 112 c thereby causing gaps definedtherebetween, along a side surface thereof, to constrict. In so doing,end effector assembly 100 is articulated in a downward direction, in thedirection of arrow “B”, i.e., in a direction transverse to longitudinalaxis “A-A”. In order to return end effector assembly 100 to anun-articulated condition or to articulate end effector assembly 100 inan opposite direction, articulation cable 94 a (i.e., the upperarticulation cable as depicted in FIGS. 8 and 9) may be withdrawn in aproximal direction by rotation of wheel 92 in an opposite direction.

Various handles and/or handle assemblies may be operatively connected orotherwise associated with end effector assembly 100 in order to effectoperation and movement of the various components thereof, i.e., drivecable 142 and/or articulation cables 94 a, 94 b. Exemplary handlesand/or handle assemblies for use with end effector 1100 are disclosed inU.S. Provisional Application Ser. No. 60/849,562 filed on Oct. 5, 2006,entitled “PROGRAMMABLE HANDLE ASSEMBLY FOR SURGICAL DEVICES”; and U.S.Provisional Application Ser. No. 60/849,560 filed on Oct. 5, 2006,entitled “HANDLE ASSEMBLY FOR ARTICULATED ENDOSCOPIC INSTRUMENTS”, theentire disclosures of each of which being incorporated herein byreference.

FIGS. 10 and 11 show one envisioned embodiment wherein the electricalleads 310 a, 310 b, 310 c and 311 are fed through the housing 20 byelectrosurgical cable 310. More particularly, the electrosurgical cable310 is fed into the bottom of the housing 20 through fixed handle 50.Lead 310 c extends directly from cable 310 into the rotating assembly 80and connects (via a fused clip or spring clip or the like) to drive rod142 to conduct the second electrical potential to jaw member 120. Leads310 a and 310 b extend from cable 310 and connect to the hand switch orjoy-stick-like toggle switch 400

In one embodiment, switch 400 may include an ergonomically dimensionedtoggle plate 405 which may conform to the outer shape of housing 20(once assembled). It is envisioned that the switch 400 permits the userto selectively activate the forceps 10 in a variety of differentorientations, i.e., multi-oriented activation. As can be appreciated,this simplifies activation. A pair of prongs 404 a and 404 b extenddistally and mate with a corresponding pair of mechanical interfaces 21a and 21 b disposed within housing 20. Toggle plate 405 mechanicallymates with a switch button 402 which, in turn, connects to an electricalinterface 401. The electrical leads 310 a and 310 b are electricallyconnected to electrical interface 401. When the toggle plate 405 isdepressed, trigger lead 311 carries the first electrical potential tojaw member 110. More particularly, lead 311 extends from interface 401through the rotating assembly 80 and along a portion of shaft 12 toeventually connect to the jaw member 110. Lead 310 c connects directlyto either drive shaft 142 which ultimately connects to jaw member 120 ormay be configured to extend directly to jaw member 120 to carry thesecond electrical potential.

It is envisioned that a safety switch or circuit (not shown) may beemployed such that the switch cannot fire unless the jaw members 110 and120 are closed and/or unless the jaw members 110 and 120 have tissueheld therebetween. In the latter instance, a sensor (not shown) may beemployed to determine if tissue is held therebetween. In addition, othersensor mechanisms may be employed which determine pre-surgical,concurrent surgical (i.e., during surgery) and/or post surgicalconditions. The sensor mechanisms may also be utilized with aclosed-loop feedback system coupled to the electrosurgical generator toregulate the electrosurgical energy based upon one or more pre-surgical,concurrent surgical or post surgical conditions. U.S. patent applicationSer. No. 10/427,832 describes one such feedback system, the entirecontents of which being incorporated by reference herein.

As mentioned above, at least one jaw member, e.g., 120, may include astop member 750 which limits the movement of the two opposing jawmembers 110 and 120 relative to one another. In one embodiment, the stopmember 750 extends from the sealing surface 122 a predetermined distanceaccording to the specific material properties (e.g., compressivestrength, thermal expansion, etc.) to yield a consistent and accurategap distance “G” during sealing. It is envisioned for the gap distancebetween opposing sealing surfaces 112 and 122 during sealing ranges fromabout 0.001 inches to about 0.006 inches and, more preferably, betweenabout 0.002 and about 0.003 inches. In one embodiment, thenon-conductive stop members 750 are molded onto the jaw members 110 and120 (e.g., overmolding, injection molding, etc.), stamped onto the jawmembers 110 and 120 or deposited (e.g., deposition) onto the jaw members110 and 120. For example, one technique involves thermally spraying aceramic material onto the surface of the jaw member 110 and 120 to formthe stop members 750. Several thermal spraying techniques arecontemplated which involve depositing a broad range of heat resistantand insulative materials on various surfaces to create stop members 750for controlling the gap distance between electrically conductivesurfaces 112 and 122.

FIGS. 15-21 show an alternate embodiment of an electrosurgicalarticulating forceps 1000 for use with vessel sealing procedures. May ofthe aforedescribed features of forceps 1000 are similar to forceps 10and for the purposes of consistency, these features are herebyincorporated in the following discussion of forceps 1000 which isdiscussed below in a more abbreviated form.

Operation of forceps 1000 is similar to forceps 10 and includes movablehandle 1040 which is movable relative to the fixed handle 1050. Movablehandle 1040 is selectively moveable about a pair of pivots 1047 and 1057(See FIG. 14C) from a first position relative to fixed handle 1050 to asecond position in closer proximity to the fixed handle 1050 which, asexplained below, imparts movement of the jaw members 1110 and 1120relative to one another. In turn, each pivot 1047 and 1057 mounts to arespective housing half 1020 a and 1020 b.

Handle 1040 is operatively coupled to a pair of linkages 1042 and 1045which upon movement of handle 1040 impart corresponding movement to thedrive assembly 1700 as explained in more detail below. The arrangementof the handles 1040 and 1050, pivots 1047 and 1057 and linkages 1042 and1045 provide a distinct mechanical advantage over conventional handleassemblies and allows the user to gain lever-like mechanical advantageto actuate the jaw members 1110 and 1120. This reduces the overallamount of mechanical force necessary to close the jaw members 1110 and1120 to effect a tissue seal.

Much like the embodiment described with respect FIGS. 1-14, the lowerend of the movable handle 1040 includes a flange 1044 which includes at-shaped distal end 1044′ that rides within a predefined channel 1051disposed within fixed handle 1050. The t-shaped distal end 1044′ lockthe movable handle 1040 relative to the fixed handle 1050 and asexplained in more detail below.

End effector assembly 1100 includes opposing jaw members 1110 and 1120which cooperate to effectively grasp tissue for sealing purposes. Theend effector assembly 1100 is designed as a unilateral assembly, i.e.,jaw member 1120 is fixed relative to the shaft 1012 and jaw member 1110pivots about a pivot pin 1134 to grasp tissue. More particularly, theunilateral end effector assembly 1100 includes one stationary or fixedjaw member 1120 mounted in fixed relation to the shaft 1012 and pivotingjaw member 1110 mounted about a pivot pin 1134 attached to thestationary jaw member 1120. A reciprocating sleeve 1230 is slidinglydisposed within the shaft 1012 and is remotely operable by the driveassembly 1700. The pivoting jaw member 1110 includes a detent orprotrusion 1113 which extends from jaw member 1110 through an aperture1232 disposed within the reciprocating sleeve 1230 (FIG. 14A). Thepivoting jaw member 1110 is actuated by sliding the sleeve 1230 axiallywithin the shaft 1012 such that a distal end of the aperture 1232 abutsagainst the detent 1113 on the pivoting jaw member 1110 (See FIGS.16A-17B). Pulling the sleeve 1230 proximally closes the jaw members 1110and 1120 about tissue grasped therebetween and pushing the sleeve 1230distally opens the jaw members 1110 and 1120 relative to one another forgrasping purposes.

Unilateral end effector assembly 1100 may be structured such thatelectrical energy can be routed through the sleeve 1230 at theprotrusion 1113 contact point with the sleeve 1230 or using a “brush” orlever (not shown) to contact the back of the moving jaw member 1110 whenthe jaw member 1110 closes. In this instance, the electrical energywould be routed through the protrusion 1113 to one of the jaw members1110 or 1120. Alternatively, an electrical cable lead 1455 may be routedto energize one of the jaw members, e.g., jaw member 1120, and the otherelectrical potential may be conducted through the sleeve 1230 viaelectrical contact with lead 1450 (See FIG. 16C) and transferred to thepivoting jaw member 1110 which establishes electrical continuity uponretraction of the sleeve 1230.

Jaw members 1110 and 1120 include similar elements to jaw members 110and 120 as described above such as jaw insulators 114 and 124 andelectrically conductive sealing surfaces 112 and 122 (See FIG. 13),respectively. Jaw member 1120 also includes a series of stop members 750(See FIG. 16B) disposed on the inner facing surface of electricallyconductive sealing surface 1122 to facilitate gripping and manipulationof tissue and to define a gap “G” (See FIG. 17A) between opposing jawmembers 1110 and 1120 during sealing and/or cutting of tissue. It isenvisioned that the series of stop members 750 may be employed on one orboth jaw members 1110 and 1120 in a variety of configurations dependingupon a particular purpose or to achieve a desired result.

Articulation assembly 1090 is operatively coupled to housing 1020.Articulation wheels 1090 a and 1090 b may be provided in alternativearrangements such as disposed on the side of housing 1020. It isenvisioned that wheels 1090 a and 1090 b may be replaced by othermechanisms to actuate the articulation assembly 1090 such as a levers,trackballs, joysticks, or the like. More particularly, as seen in thecomparison of FIGS. 18A-18C upon selective rotation of one the wheels1090 a, 1090 b, the end effector assembly 1100 may be articulated froman axially aligned condition (FIG. 18B) to an articulated condition(FIG. 18C). In order to articulate end effector assembly 1100 viaarticulation assembly 1090, wheels 1090 a and 1090 b are configured torotate in a first direction to move end effector assembly 1100 in acorresponding first direction and rotate in an opposite direction tomove end effector assembly 1100 in an opposite direction. Various pulleyassemblies and gearing assemblies may be employed to accomplish thispurpose.

For example and similar to the articulation arrangement described above,two articulation cables 1094 a and 1094 b may be utilized to articulatethe flexible portion 1012 b of shaft 1012. As best seen in FIG. 16C,each articulation cable 1094 a and 1094 b includes a distal end 1094 a′and 1094 b′ which operatively connects with an end effector couplingassembly 1016 disposed at the distal end of shaft 1012. Couplingassembly 1016 includes a cavity 1225 defined therein configured toreceive a series of mechanically inter-cooperating elements which aredesigned to engage the drive rod 1142 for reciprocation therein as wellas guide the various electrical connections to the jaw members 1110 and1120. The drive rod 1142 is preferably made from a flexible,friction-reducing material to allow the drive rod 1142 to bend in agiven direction when the forceps 1000 is articulated. Thefriction-reducing material reduces buckling during articulation.

Coupling assembly includes a pair of bushings 1220 and 1240 which engageand secure a distal end 1142′ of the drive rod 1142 to the drive sleeve1230 via pin 1231. Bushing 1240 is slidingly engaged atop drive rod 1142proximal to end 1142′ and bushing 1220 is configured to engage bushing1240 and secure end 1142′ therebetween. Pin 1231 couples the securedbushings 1240 and 1220 and drive rod 1142 to drive sleeve 1230. Thedrive sleeve 1230 (and secured drive rod 1142) is received within cavity1225 for sliding translation therein upon actuation of the driveassembly 1700 as explained in more detail below.

Coupling assembly 1016 also includes a locking element 1210 which isconfigured to engage a proximal end 1117 of jaw member 1120 to lock thecoupling assembly 1016 (and drive rod 1142) in fixed relation relativeto jaw member 1120 to limit any rotational movement therebetween. Thecoupling assembly 1016 also includes a distal flange 1017 which supportsthe lower jaw member 1120 once assembled (See FIG. 14A). As best shownin FIG. 16C, the coupling assembly 1016 also supports the electricalconnection between lead 1450 and driving sleeve 1230. In addition,coupling assembly 1016 also guides electrical lead 1455 (shown inphantom) therethrough for connection to jaw member 1110.

In operation, movement of one of the articulation wheels 1090 a and 1090b results in movement of the articulation cables 1094 a and 1094 b inopposite directions. More particularly, and as best shown in FIGS. 14C,18A, 20A and 20B, the articulation assembly 1090 include wheels 1090 aand 1090 b which matingly couple to corresponding gear members 1096 aand 1096 b disposed on respective sides of housing 1020 a and 1020 b(See FIG. 20A). A hexagonal axle 1095 is mounted through both gearmembers 1096 a and 1096 b and capped on either end by wheels 1090 a and1090 b. The axle 1095 is secured within the gear members 1096 a and 1096b by mechanically mating surfaces (friction fit, geometric fit, etc.) orin other ways customary in the trade. The gear-like arrangement of thewheels 1090 a and 1090 b allow for incremental indexing of thearticulation member 1090 in a given direction and a pair of set springs1091 on each wheel prevent recoil of the wheel in any given direction.In other words, the set springs 1091 are configured to intermesh withthe gears, e.g., gear 1096 b, and allow incremental advancement in aclockwise or counter-clockwise direction. The biasing force of the setsprings 1091 against the gear, e.g., gear 1096 b, is sufficient tomaintain the flexible shaft 1012 b in any desired articulated position.

Axle 1095 supports pulley assembly 1600 within housing 1020 in operativeassociation with cables 1094 a and 1094 b. More particularly, pulleyassembly 1600 includes two pulleys 1610 a and 1610 b mounted forrotation atop axle 1095. Each pulley 1610 a and 1610 b includes acorresponding guide sleeve 1620 a and 1620 b which guide the respectivecable 1094 a and 1094 b atop the corresponding pulley 1610 a and 1610 bto facilitate reciprocation thereof. As best shown in FIG. 18A, cable1094 a is designed to engage pulley 1620 b for rotation one direction,while cable 1094 b is designed to engage pulley 1620 a for rotation inthe opposite direction. As can be appreciated, this enables the pulleys1610 a and 1610 b to operate in a push—pull manner to articulate theflexible shaft 1012 b. In other words, as one cable 1094 a is beingpulled in the direction of P1, the other cable 1094 b is being pushed(or relaxed) in the direction of P2 to allow the flexible shaft 1012 bto articulate in a given direction (See FIG. 18C). The guide sleeves1620 a and 1620 b also pre-tension the respective cables 1094 b and 1094a to facilitate and enhance consistent articulation of the flexibleshaft 1012 b.

As best seen ion FIG. 14B, the drive assembly 1700 also includes a fineadjustment assembly 1061 operably associated with drive rod 1142 whichallows a manufacturer to finely adjust the opening of the jaw members1110 and 1120 relative to one another prior to final assembly. Moreparticularly, the drive rod 1142 is connected to an adapter 1063 which,in turn, connects to drive rod 1142 a connected to drive assembly 1700as describe below. Adapter 1063 is threaded at a distal end thereof tothreadably engage an adjustment knob 1067 to allow a manufacturer tofinely adjust the length of the drive rode 1142 relative to the driveassembly 1700 thereby allowing the relative separation distance of thejaw members 1110 and 1120 to be accurately and finely controlled.

As best shown in FIGS. 14C, 15A, 15B, 19A and 19B, actuation of thedrive assembly 1700 allows a user to selectively open and close the jawmembers 1110 and 1120 to grasp and seal tissue. More particularly, thedrive assembly 1700 includes a frame block 1800 which operably mounts acompression spring 1740 that biases the drive rod 1142 and couplingdrive rod 1142 a thereagainst. The coupling drive rod 1142 a mounts to adrive block 1710 which, in turn, is coupled to the distal end of frameblock 1800 by adapter 1720. When assembled, the frame block 1800 isdisposed between opposing rails 1021 defined in housing halves 1020 aand 1020 b (See FIG. 14C) which permit the frame block 1800 to movewithin the housing 1020 upon actuation of handle 1040. Spring 1740 ismounted between a spacer 1730 (disposed adjacent adapter block 1720) andthe proximal end 1810 of frame block 1800. A drive pin 1750 mounts tothe opposite end of drive block 1710 and supports the compression spring1740 to enable movement of the drive rod 1142.

As mentioned above, handle 1040 is operable mounted to the driveassembly 1700 such that movement of the handle 1040 relative to handle1050 translates the drive rod 1142 to open and close the jaw members1110 and 1120. More particularly, handle 1040 is mounted at a top ordistal end thereof via pin 1047 to link 1045 which, in turn, mounts toframe block 1800 also via pin 1047. Handle 1040 is also mounted to link1042 at pivot point 1041 which, in turn, mounts to handle 1050 at pivot1057 to complete the four bar mechanical assembly. As best shown in thecomparison of FIGS. 19A and 19B, movement of handle 1040 towards handle1050 rotates the two links 1042 and 1045 to force the frame block 1800proximally and pull the drive rod 1142 a proximally (which pulls driverod 1142 proximally) to close the jaw members 1110 and 1120. A the sametime, flange 1044 operably coupled to the bottom of handle 1040,reciprocates into a guide channel 1051 defined in handle 1050 such thata t-shaped end 1044′ locks the handle 1040 in place relative to handle1050. Flange 1044 and channel 1051 operate in a similar manner asdescribed above with respect to forceps 10.

Spring 1740 includes two opposing compression discs 1740 a and 1740 bdisposed therein which slidingly mount atop drive pin 1750. Uponmovement to of handle 1040 towards handle 1050, spring disc 1740 a isforced by movement of adapter 1720 to compress atop drive pin 1750 andpull the drive rod 1142 proximally. As mentioned above, movement of thedrive rod 1142 proximally, causes the drive sleeve 1230 to engage flange1113 of jaw member 1110 and close jaw members 1110 relative to jawmember 1120. Flange 1044 thereafter locks the handle 1040 relative tohandle 1050 by virtue of the t-shaped end 1044′ engaging a catch basin1052 defined in the handle 1050. Upon re-grasping of handle 1040, thet-shaped end 1044′ on flange 1044 is redirected out of channel 1051 tofree handle 1040 for movement away from handle 1050. Spring 1740 biasesthe handle 1040 in an open orientation.

As mentioned above, jaw member 1120 may include a series of stop members750 disposed on the inner facing surfaces of the electrically conductivesealing surface 1122 to facilitate gripping and manipulation of tissueand to define a gap “G” (see FIG. 17A) between opposing jaw members 1110and 1120 during sealing and cutting of tissue. The preferred gap “G”between the conductive sealing surfaces 1112 and 1122 to effectively andreliably seal tissue is between about 0.001 and about 0.006 inches. Thestop members 750 may be disposed in any configuration along theelectrically conductive jaw surfaces 1112 and 1122 depending upon aparticular jaw configuration or desired surgical result.

The end effector assembly 1100 may also be articulated in eitherdirection (See arrow “B-B”) as shown with reference to FIG. 18A. Oncethe tissue is grasped (within the required pressure range of about 3kg/cm² to about 16 kg/cm²), the user then selectively applieselectrosurgical energy to effectively seal tissue. Once sealed, the usermay then selectively advances a knife (not shown) by actuating a triggerassembly (not shown) to cut the tissue along the tissue seal. Theoperating features and relative movements of one envisioned knife andtrigger assembly are described above and also described with referenceto U.S. patent application Ser. No. 10/460,926, the entire contentsbeing incorporated herein.

Similar to FIGS. 2 and 3 above, the forceps 1000 includes a plurality ofjoints 1312 which are nestingly arranged in series to form flexibleshaft 1012 b. The distal end or coupling assembly 1016 mechanicallyengages the end effector assembly 1100 and the proximal end 1014 of theshaft 1012 mechanically engages the housing 1020. Each of the pluralityof joints 1312 of the flexible shaft 1012 b includes a distal knuckle1312 a and a proximal clevis 1312 b formed therewith. Each knuckle 1312a operatively engages a clevis 1312 b of an adjacent joint 1312 a. Eachjoint 1312 has a central lumen 1317 defined therein and a pair ofopposed lumens 1315 a and 1315 b formed on either side of central lumen1317. The articulation cables 1094 a and 1094 b slideably extend throughrespective lumens 1315 a and 1315 b of joints 1312. The operation ofcables 1094 a and 1094 b is explained above. The articulation cables1094 a and 1094 b are preferably made from a flexible, friction-reducingmaterial.

A switch 2000 is included which may conform to the outer shape ofhousing 1020 (once assembled). It is envisioned that the switch 2000permits the user to selectively activate the forceps 1000 in a varietyof different orientations, i.e., multi-oriented activation. As can beappreciated, this simplifies activation. A push button 2010 extendsdistally and engages a toggle plate 2015 (See FIG. 15B) which, in turn,connects to an electrical interface or PC Board (not shown). Electricalleads 2025 a and 2025 b internally disposed in cable 2020 (See FIG. 19)electrically connect to electrical interface or PC board. When the pushbutton 2010 is depressed, the leads 2025 a and 2025 b carry electricalpotentials to the jaw members 1110 and 1120.

It is envisioned that a safety switch or circuit (not shown) may beemployed such that the switch cannot fire unless the jaw members 1110and 1120 are closed and/or unless the jaw members 1110 and 1120 havetissue held therebetween. In the latter instance, a sensor (not shown)may be employed to determine if tissue is held therebetween. Inaddition, other sensor mechanisms may be employed which determinepre-surgical, concurrent surgical (i.e., during surgery) and/or postsurgical conditions. The sensor mechanisms may also be utilized with aclosed-loop feedback system coupled to the electrosurgical generator toregulate the electrosurgical energy based upon one or more pre-surgical,concurrent surgical or post surgical conditions. U.S. patent applicationSer. No. 10/427,832 describes one such feedback system, the entirecontents of which being incorporated by reference herein.

Various handles and/or handle assemblies may be operatively connected orotherwise associated with end effector assembly 1100 in order to effectoperation and movement of the various components thereof, i.e., driverod 1142 and/or articulation cables 1094 a, 1094 b. Exemplary handlesand/or handle assemblies for use with end effector 1100 are disclosed inU.S. Provisional Application Ser. No. 60/849,562 filed on Oct. 5, 2006,entitled “PROGRAMMABLE HANDLE ASSEMBLY FOR SURGICAL DEVICES”; and U.S.Provisional Application Ser. No. 60/849,560 filed on Oct. 5, 2006,entitled “HANDLE ASSEMBLY FOR ARTICULATED ENDOSCOPIC INSTRUMENTS”, theentire disclosures of each of which being incorporated herein byreference.

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the same. For example, it is contemplated that the forceps 10 (and/orthe electrosurgical generator used in connection with the forceps 10)may include a sensor or feedback mechanism (not shown) whichautomatically selects the appropriate amount of electrosurgical energyto effectively seal the particularly-sized tissue grasped between thejaw members 110 and 120. The sensor or feedback mechanism may alsomeasure the impedance across the tissue during sealing and provide anindicator (visual and/or audible) that an effective seal has beencreated between the jaw members 110 and 120. Examples of such sensorsystems are described in commonly-owned U.S. patent application Ser. No.10/427,832 entitled “METHOD AND SYSTEM FOR CONTROLLING OUTPUT OF RFMEDICAL GENERATOR” filed on May 1, 2003 the entire contents of which arehereby incorporated by reference herein.

As can be appreciated, locating the switch 400, 2000 on the forceps 10,1000 has many advantages. For example, the switch 400, 2000 reduces theamount of electrical cable in the operating room and eliminates thepossibility of activating the wrong instrument during a surgicalprocedure due to “line-of-sight” activation. Moreover, it is envisionedthat the switch 400, 2000 may be decommissioned during activation of theknife 185. Decommissioning the switch 400, 2000 when the trigger isactuated eliminates unintentionally activating the forceps 10, 1000during the cutting process. It is also envisioned that the switch 400,2000 may be disposed on another part of the forceps 10, 1000, e.g., thehandle 40, 1040, rotating assembly 80, housing 20, etc.

Another envisioned safety mechanism would be to route one of he cableleads to energize the one jaw member, e.g., jaw member 1120, and theother electrical potential may be conducted through a drive sleeve,e.g., drive sleeve 1230, surrounding drive rod 1142 and transferred tothe other jaw member 1110 to establish electrical continuity only uponretraction of the drive sleeve. It is envisioned that this particularenvisioned embodiment will provide at least one additional safetyfeature, i.e., electrical continuity to the jaw members 1110 and 1120 ismade only when the jaw members 1110 and 1120 are closed. The drive rod1142 may also be energized to the second electrical potential andinclude a similar-type safety mechanism.

In one envisioned embodiment, the knife 185 may not be included with theforceps 10, 1000 and the instrument is designed solely for sealingvessels or other tissue bundles. In this instance, the camming hub 144(with respect to forceps 10 only) may be rotated to articulate the endeffector assembly 100 and cables 94 a and 94 b may be eliminated.

In one embodiment, two isolated electrical leads may supply electricalenergy to respective jaw members 110 and 120 (or 1110 and 1120). In thisinstance it may be desirable to provide a channel along the outside ofshaft 12, 1012 which guides the electrical leads from the housing 20,1020 to the individual jaw members 110, 120 (or 1110 and 1120) One ormore wire crimps or the like may be utilized to hold the electricalleads in place. Alternatively, cables 94 a and 94 b (or 1094 a and 1094b) may be utilized to both articulate the end effector assembly 100 (or1100) and to supply electrical energy to the jaw members 110 and 120 (or1110 and 1120).

With particular respect to forceps 10 in particular but nor exclusively,the cable lead, e.g., cable lead 311 of forceps 10 is held loosely butsecurely along the cable path to permit rotation of the jaw member 110about pivot 103. The two potentials are isolated from one another byvirtue of the insulative sheathing surrounding cable lead 311. Moreover,the proximal portion of shaft 12 may be rigid or substantially rigid andthe distal portion is flexible and/or articulateable in the mannerdescribed in more detail above. Alternatively, the entire shaft 12 maybe flexible. Still further, the trigger assembly 70 may be preventedfrom firing until movable handle 40 is locked (or simply moved)proximally to close the jaw members 110 and 120.

In embodiment relating to both forceps 10, 1000, the electricallyconductive sealing surfaces 112,122 and 1112, 1122 of the jaw members110, 120 and 1110, 1120, respectively, are relatively flat to avoidcurrent concentrations at sharp edges and to avoid arcing between highpoints. In addition and due to the reaction force of the tissue whenengaged, jaw members 110, 120 and 1110, 1120 can be manufactured toresist bending. For example, the jaw members 110, 120 and 1110, 1120 maybe tapered along the width thereof which resists bending due to thereaction force of the tissue.

It is envisioned that the outer surface of the end effector assembly100, 1100 may include a nickel-based material, coating, stamping, metalinjection molding which is designed to reduce adhesion between the jawmembers 110, 120 and 1110, 1120 with the surrounding tissue duringactivation and sealing. Moreover, it is also contemplated that theconductive surfaces 112, 122 and 1112 and 1122 of the jaw members 110,120 and 1110, 1120, respectively, may be manufactured from one (or acombination of one or more) of the following materials: nickel-chrome,chromium nitride, MedCoat 2000 manufactured by The ElectrolizingCorporation of OHIO, inconel 600 and tin-nickel. The tissue conductivesurfaces 112, 122 and 1112 and 1122 may also be coated with one or moreof the above materials to achieve the same result, i.e., a “non-sticksurface”. As can be appreciated, reducing the amount that the tissue“sticks” during sealing improves the overall efficacy of the instrument.

One particular class of materials disclosed herein has demonstratedsuperior non-stick properties and, in some instances, superior sealquality. For example, nitride coatings which include, but not are notlimited to: TiN, ZrN, TiAIN, and CrN are preferred materials used fornon-stick purposes. CrN has been found to be particularly useful fornon-stick purposes due to its overall surface properties and optimalperformance. Other classes of materials have also been found to reducingoverall sticking. For example, high nickel/chrome alloys with a Ni/Crratio of approximately 5:1 have been found to significantly reducesticking in bipolar instrumentation. One particularly useful non-stickmaterial in this class is Inconel 600. Bipolar instrumentation havingsealing surfaces 112, 122 and 1112 and 1122 made from or coated withNi200, Ni201 (˜100% Ni) also showed improved non-stick performance overtypical bipolar stainless steel electrodes.

Forceps 10, 1000 may be designed such that it is fully or partiallydisposable depending upon a particular purpose or to achieve aparticular result. For example, end effector assembly 100, 1100 may beselectively and releasably engageable with the distal end of the shaft12, 1012 and/or the proximal end 14, 1014 of shafts 12, 1012 may beselectively and releasably engageable with the housing 20, 1020. Ineither of these two instances, the forceps 10, 1000 would be considered“partially disposable” or “reposable”, i.e., a new or different endeffector assembly 100, 1100 (or end effector assembly 100, 1100 andshaft 12, 1012) selectively replaces the old end effector assembly 100,1100 as needed. As can be appreciated, the presently disclosedelectrical connections would have to be altered to modify the instrumentto a reposable forceps.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of theclaims appended hereto.

1. An electrosurgical instrument for treating tissue, comprising: ahousing having a flexible shaft extending therefrom having an axis A-Adefined therethrough, the shaft including first and second jaw membersattached at a distal end thereof, each jaw member including anelectrically conductive tissue contacting surface adapted to connect toa source of electrosurgical energy such that the electrically conductivetissue contacting surfaces are capable of conducting electrosurgicalenergy through tissue held therebetween; a drive assembly disposed inthe housing including a first actuator operably coupled to a drive rodfor reciprocation thereof and a second actuator operably coupled to thedrive rod for rotation thereof; and a knife operably coupled to a distalend of the drive rod; wherein actuation of the first actuator moves thejaw members from a first position in spaced relation to one another to asecond position closer to one another for engaging tissue and actuationof the second actuator rotates the drive rod about the axis A-A totranslate the knife to cut tissue disposed between the jaw members. 2.An electrosurgical instrument for treating tissue according to claim 1further comprising a cam assembly coupled to the distal end of the driverod, the cam assembly including a camming hub having a grooved outerperiphery defined therein which is configured to matingly engage acorresponding detent disposed on the knife wherein rotational movementof the drive rod correspondingly rotates the camming hub which, in turn,translates the detent and knife relative to the jaw members.
 3. Anelectrosurgical instrument for treating tissue according to claim 2wherein the cam assembly also includes a coupling device configured tocouple the drive rod to the camming hub.
 4. An electrosurgicalinstrument for treating tissue according to claim 3 wherein the couplingdevice includes a keyed rod configured at one end to interface with thedrive rod and configured at an opposite end to matingly engage akey-like aperture defined in the camming hub.
 5. An electrosurgicalinstrument for treating tissue according to claim 1 wherein the flexibleshaft includes a plurality of joints nestingly arranged in series toform at least a portion of the flexible shaft.
 6. An electrosurgicalinstrument for treating tissue according to claim 5 wherein each jointincludes at least one lumen defined therethrough for allowingreciprocation of the drive rod therein.
 7. An electrosurgical instrumentfor treating tissue according to claim 5 wherein each joint includes acentral lumen formed therein and a pair of opposed lumens formed oneither side of the central lumen and wherein the electrosurgicalinstrument includes a pair of articulation cables slideably extendablethrough the respective opposed lumens which are moveable relative to oneanother to articulate the shaft relative to axis A-A.
 8. Anelectrosurgical instrument for treating tissue according to claim 7further comprising a third actuator operably coupled to the housing formoving the pair of articulation cables relative to one another toarticulate the flexible shaft relative to axis A-A.
 9. Anelectrosurgical instrument for treating tissue, comprising: a housinghaving a flexible shaft extending therefrom including an axis A-Adefined therethrough; an end effector assembly attached at the distalend of the shaft, the end effector including a clevis which supportsfirst and second jaw members about a pivot pin such that the jaw membersare moveable between a first spaced apart position relative to oneanother to a second position in closer relation relative to one another,each jaw member including an electrically conductive tissue contactingsurface adapted to connect to a source of electrosurgical energy suchthat the electrically conductive tissue contacting surfaces are capableof conducting electrosurgical energy through tissue held therebetween,the jaw members each including an angled cam surface defined therein andthe clevis including a slot defined therein; a knife operably coupled toa distal end of the drive rod; a drive assembly disposed in the housingincluding a first actuator operably coupled to a drive rod forreciprocation thereof and a second actuator operably coupled to thedrive rod for rotation thereof, the distal end of the drive rodconfigured to receive a drive pin which engages both the cam surfacedefined in the jaw members and the slot defined in the clevis such thatactuation of the first actuator reciprocates the drive pin to move thejaw members from a first position in spaced relation to one another to asecond position closer to one another for engaging tissue and actuationof the second actuator rotates the drive rod about the axis A-A totranslate the knife to cut tissue disposed between the jaw members. 10.An electrosurgical instrument for treating tissue according to claim 9further comprising a cam assembly coupled to the distal end of the driverod, the cam assembly including a camming hub having a grooved outerperiphery defined therein which is configured to matingly engage acorresponding detent disposed on the knife wherein rotational movementof the drive rod correspondingly rotates the camming hub which, in turn,translates the detent and knife relative to the jaw members.
 11. Anelectrosurgical instrument for treating tissue according to claim 10wherein the drive rod is slidingly received within the camming hub. 12.An electrosurgical instrument for treating tissue according to claim 10wherein the cam assembly also includes a coupling device configured tocouple the drive rod to the camming hub.
 13. An electrosurgicalinstrument for treating tissue according to claim 12 wherein thecoupling device includes a keyed rod configured at one end to interfacewith the drive rod and configured at an opposite end to matingly engagea key-like aperture defined in the camming hub.
 14. An electrosurgicalinstrument for treating tissue according to claim 9 wherein the flexibleshaft includes a plurality of joints nestingly arranged in series toform at least a portion of the flexible shaft.
 15. An electrosurgicalinstrument for treating tissue according to claim 14 wherein each jointincludes at least one lumen defined therethrough for allowingreciprocation of the drive rod therein.
 16. An electrosurgicalinstrument for treating tissue according to claim 14 wherein each jointincludes a central lumen formed therein and a pair of opposed lumensformed on either side of the central lumen and wherein theelectrosurgical instrument includes a pair of articulation cablesslideably extendable through the respective opposed lumens which aremoveable relative to one another to articulate the shaft relative toaxis A-A.
 17. An electrosurgical instrument for treating tissueaccording to claim 16 further comprising a third actuator operablycoupled to the housing for moving the pair of articulation cablesrelative to one another for articulating the flexible shaft relative toaxis A-A.